Experiments on three closely related topics in animal conditioning are proposed. First, the research will determine the reward-specificity of conditioned inhibitors (CIs) on the operant behavior of pigeons. Reward-specific CIs will be established by combining a stimulus with a predictor of food (or water) but leaving the compound unreinforced. The CIs will be tested in reward-specific retardation or combined-cue tests. Second, the reward-specificity of reactions to nonreward will be explored using a two-choice conditional discrimination procedure. In these experiments, stimulus feedback from reactions to the nonpresentation of specific rewards will serve as differential conditioned excitors (CEs) of operant responses. Pigeons will be rewarded for making one particular choice response after having encountered nonpresentation of expected food reward; they will be rewarded for making the other choice response following nonpresentation of expected water reward. The transfer of these choice responses to the same kinds of disappointments under different conditions will also be studied. Third, the hypothesis that conditioned inhibition actually involves excitatory conditioning of reactions to nonreward will be examined by combining methodological features of the former two problem areas. Differential choice responses will be conditioned to feedback stimuli of reactions to specific nonreward. Then, using different stimuli, reward-specific CIs will be established. Finally, these CIs will be presented in combination with the choice behavior cues. If the CIs evoke conditioned nonreward reactions, they should facilitate choice behavior following appropriate nonreward. On the other hand, if CIs have a more central effect, they should inhibit choice behavior on those trials. The research in all three areas should contribute to determining the relative validities of cognitive and behavioral theories of inhibition.